This research is to study genetic miscoding by metals. the rationale is based on the hypothesis that decreased fidelity of DNA synthesis by metal ions is associated with metal-induced mutagenesis and/or carcinogenesis. The aims are: (1) to determine the mechanism by which metal ions alter the fidelity of DNA synthesis in vitro; (2) to investigate whether particular metal ions bind to specific nucleotides and change the specificity of base-pairing; and (3) to analyze the relationship of this miscoding to mutations and malignancy. Genetic miscoding by metal ions will be analyzed by: (1) measuring the frequency of non-complementary nucleotide incorporation with purified DNA polymerases and synthetic polynucleotide templates; (2) quantitating mutation rates after copying biologically active DNA by DNA polymerases in vitro; (3) studying DNA replication and DNA repair in bacterial spheroplasts and human lymphocytes; and (4) determining the amounts of trace metals associated with chromatin and DNA in normal and malignant cells. In addition, a biochemical assay, based on alteration in the fidelity of DNA synthesis in vitro will be developed to screen for potential mutagens and/or carcinogens. Our current assay will be modified to use purified DNA polymerase-alpha from human placenta, poly (d(A-T)) as a template, and a microsomal-carcinogen activating system.